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| author | Richard Biener <rguenther@suse.de> | 2014-06-26 11:29:34 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2014-06-26 11:29:34 +0000 |
| commit | 73c7d6bc25d9bb86bdb81283d237a5b94607ac8c (patch) | |
| tree | 1c939200ec3ae5f46afa0de763e00de9f4d4e65b /gcc/tree-ssa-dom.c | |
| parent | 1d805a56b6a5c2252baccd257e00a719a22ad143 (diff) | |
| download | gcc-73c7d6bc25d9bb86bdb81283d237a5b94607ac8c.zip gcc-73c7d6bc25d9bb86bdb81283d237a5b94607ac8c.tar.gz gcc-73c7d6bc25d9bb86bdb81283d237a5b94607ac8c.tar.bz2 | |
re PR tree-optimization/61607 (DOM missed jump threading and destroyed loops)
2014-06-26 Richard Biener <rguenther@suse.de>
PR tree-optimization/61607
* tree-ssa-copy.c (copy_prop_visit_phi_node): Adjust comment
explaining why we restrict copies on loop depth.
* tree-ssa-dom.c (cprop_operand): Remove restriction on
on loop depth.
(record_equivalences_from_phis): Instead add it here.
* gcc.dg/tree-ssa/ssa-dom-thread-5.c: New testcase.
From-SVN: r212026
Diffstat (limited to 'gcc/tree-ssa-dom.c')
| -rw-r--r-- | gcc/tree-ssa-dom.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 62444b2..795ed09 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -1234,7 +1234,13 @@ record_equivalences_from_phis (basic_block bb) this, since this is a true assignment and not an equivalence inferred from a comparison. All uses of this ssa name are dominated by this assignment, so unwinding just costs time and space. */ - if (i == gimple_phi_num_args (phi) && may_propagate_copy (lhs, rhs)) + if (i == gimple_phi_num_args (phi) + && may_propagate_copy (lhs, rhs) + /* Do not propagate copies if the propagated value is at a deeper loop + depth than the propagatee. Otherwise, this may introduce uses + of loop variant variables outside of their loops and prevent + coalescing opportunities. */ + && !(loop_depth_of_name (rhs) > loop_depth_of_name (lhs))) set_ssa_name_value (lhs, rhs); } } @@ -2247,14 +2253,6 @@ cprop_operand (gimple stmt, use_operand_p op_p) if (!may_propagate_copy (op, val)) return; - /* Do not propagate copies if the propagated value is at a deeper loop - depth than the propagatee. Otherwise, this may move loop variant - variables outside of their loops and prevent coalescing - opportunities. If the value was loop invariant, it will be hoisted - by LICM and exposed for copy propagation. */ - if (loop_depth_of_name (val) > loop_depth_of_name (op)) - return; - /* Do not propagate copies into simple IV increment statements. See PR23821 for how this can disturb IV analysis. */ if (TREE_CODE (val) != INTEGER_CST |